RDD
    map filter reduce reduceByKey  ...

    mane sal age .....
dataset
    A Dataset is a distributed collection of data
    数据集 是分布式的数据集合

dataframes
    A DataFrame is a Dataset organized into named columns
    DataFrame是以列名组织的数据集
    Throughout this document, we will often refer to
        Scala/Java Datasets of Rows as DataFrames.
    在整个文档中，我们经常将Scala/Java行数据集称为DataFrames。
    DataFrame是一个特殊的RDD